Data communication system including automatic information transfer control means

ABSTRACT

A data communication system for transferring messages between a plurality of remote terminals and a working store includes an information transfer and director. The information transfer and director selectively receives messages from the terminals, adds a message identifier to each message representing currency (software processing of message required), stores the messages in the working store, selectively tests for the presence of the message identifier in the messages previously stored, and inhibits the transmittal of messages from the terminals to the information transfer and director when the number of previously stored messages exceeds a predetermined number.

United States Patent [72] Inventors John F. Baltzly; 3,369,221 2/1968 Lethin et al 340/l72.5 Donn E. Bernhardt; Edward II. Cabaniss, 3,500,333 3/1970 Couleur et al. 340/ 172.5 III; Perry W. Penton, all of Phoenix, Ariz. Primary Examiner Raulfg B- Zache [211 App]. No. 845,398

Assistant Examiner-Melvin B. Chapmck [22] Flled July 1969 Atmmeys- Edward W Hughes and Fred Jacob [45] Patented Nov. 2, 1971 a [73] Assignee Honeywell Information Systems Inc.

54 DATA COMMUNICATION SYSTEM INCLUDING l 1 AUTOMATIC INFORMATION TRANSFER ABSTRACT: A data communication system for transferring CONTROL MEANS messages between a plurality of remote terminals and a work- 6 Chin 27 Drawing Figs ing store includes an information transfer and director. The information transfer and director selectively receives messages [52] 0.8. CI 340/1715 from the terminals, adds a message identifier to each message 11W Cl G06! 9/18 representing currency (software processing of message Search 235/157; required), stores the messages in the working store, selectively 340/1725 tests for the presence of the message identifier in the messages previously stored, and inhibits the transmittal of messages [56] Rd'rences Cited from the terminals to the information transfer and director UNITED STATES PATENTS when the number of previously stored messages exceeds a 3,181,124 4/1965 Hammel 340/l72.5 predetermined number.

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1. A data communications system comprising: A. a data processor including a memory having a plurality of individually addressable storage locations, each of said storage locations capable of holding an information item; B. address generating means connected to said data processor for forming an address of a storage location to receive information items; C. a source external to said processor for furnishing information items to said memory for retention therein; D. control means connected to said address generating means for modifying the formed address of the storage location, remote from that location addressed; E. inhibiting means connected to said source and connected to said data processor to receive an information item from the location at the modified address for inhibiting the furnishing of additional information items from said source in response to a prescribed configuRation of said contents of said location at the modified address.
 2. means to periodically load said register means with a character identifying which said scanner received the current message and a prescribed character representing status for subsequent use by said second decoder,
 2. receive scan control means connected to said register means for selectively receiving characters from a data terminal,
 2. A data communication system comprising: A. a plurality of terminals adapted to transmit units of message information in response to interrogation signals; B. a data processor, said processor including a memory having a plurality of selectively addressable storage locations, each of said locations capable of retaining a unit of message information, portions of selected ones of said units including a message identifier, said memory acting to store incoming units of message information in response to storage location addresses provided thereto; C. a communications controller connected intermediate said processor and said terminals, said controller including,
 2. means for acting upon units of message information to be stored in said memory by the addition thereto of a message identifier, and
 2. means responsive to said command signal to prevent the continued generation of interrogation signals whereby said terminals cease to transmit said units of message information.
 2. transmit selector means connected to said address generating means for providing data to select memory locations for servicing respective data terminals,
 2. receive selector connected to said address generating means for providing data to select memory locations, for servicing a current data terminal and a second data terminal,
 2. an outgoing register and an incoming register, connected to said transmitters and receivers, respectively, for buffering character data for said data terminals,
 3. a receive controller for producing first and second signals for respectively initiating transfer of data to said memory from said current data terminal and subsequently to transfer previously received data to said second data terminal from said memory.
 3. a transmit controller for producing signals for a data processor to initiate transfer of data from said memory to said communications controller,
 3. An information transfer controller and director, for providing data communications capability for a data processor for messages comprised of a string of characters, comprising: A. register means including control logic for transferring data characters to and from a data terminal; B. a decoder connected to said register means for detecting prescribed data characters appearing at a prescribed location in a message transmission; C. inhibiting means connected to said decoder and said register means for inhibiting transfer of characters from a data terminal to said register means in response to said decoder decoding a first prescribed data character and for removing transfer inhibition upon decoding a second prescribed data character; D. communications controller means, connected to said register means for interfacing said register means and a data processor.
 3. means for testing for the presence of a message identifier in units of message information retrieved from said memory and for the generation of a command signal in response to the presence of said message identifier; D. and scanning means intermediate said communication controller and said terminals for polling said terminals, said scanning means including
 3. transmit scan control means including a first decoder connected to said register means for selecting a data terminal for transmission in accordance with a character in a prescribed location in a message transmission,
 3. address generating means for producing addresses for a working store memory in accordance with the selection of scanners for transmission and reception,
 3. a counting controller connected to said receivers for sequentially scanning said terminals for incoming messages,
 4. an address register connected to said outgoing register for receiving data representing data terminal selection, said address register also being connected to said transmitters for selectively directing message characters from said outgoing register through said transmitters,
 4. control means for generating signals for a data processor for transferring words from said word register means to a data processor memory for incoming messages and for transferring words to said word register means for outgoing messages and incoming messages in such a manner that said scanners test said prescribed character representing status.
 4. An information transfer controller and director as set forth in claim 3, further including: E. central transmit control means including
 4. data transfer means connected to said scanners for transferring data from said memory to said scanners; F. central receive control means including
 4. inhibiting means including a second decoder connected to said register means for starting and stopping said receive scan control means in accordance with prescribed characters in said prescribed location in a message transmission; B. a communications controller including
 5. a start/stop decoder connected to said counting controller for inhibiting scanning of said receivers when activated, thereby stopping message reception, said start/stop decoder being connected to said address register for sensing predetermined addresses indicative of start and stop message reception conditions,
 5. An information transfer controller and director comprising: A. a plurality of scanners, each scanner including
 6. An information transfer controller and director comprising: A. a plurality of scanners, each scanner including
 6. a start of message decoder connected to said outgoing register for selectively gating data to said address register upon decoding a start of message character; B. word register means connected to said scanners for holding data characters for transmission and reception, said word registers being adapted to receive and transmit message words to and from a data processor; C. base address generating means for providing message queue addresses for the working store memory; D. word address generating means connected to said base address generating means for producing absolute memory addresses of message words for the working store memory; E. receive control means connected to said word address generating means including logic for automatically initiating a read memory cycle for checking the receive message queue for processor overload by modifying the address in said word address generating means for the current received message to a look-ahead address in the receive queue and initiating a message transmission from a data processor whereby said start/stop decoder tests for message recEption termination. 